This invention is in the field of electric drip coffee makers, and particularly the type were a quantity of ground coffee is placed in a brewing basket, and a quantity of water in a reservoir is heated and caused to flow through the ground coffee, whereby the coffee is brewed and then discharged into a receptacle. Typically, the brewing basket has spaced inlet apertures in the top for distributing the hot water relatively uniformly as it drips into the coffee grounds, and exit apertures in the bottom through which brewed coffee is discharged. Also, the brewing basket may include a by-pass tube, whereby excess heated water can by-pass the coffee grounds and flow directly into the receptacle, to reduce excessive water and resultant foaming in the brewing basket and to avoid excessive brewing time.
For the purpose of describing and comparing coffee brewed by different apparatus and different recipes, certain standards have been eestablished by the Coffee Brewing Center (CBC) of the Pan American Coffee Bureau, an independent organization promoting higher standards for coffee making. According to the CBC coffee strength is acceptable in the range of hydrometer readings of 1.15 .+-. 5% for weak coffee to 1.35 .+-. 5% for strong coffee, which allows an overall acceptable range of hydrometer readings from 1.09 to 1.42.
To consistently produce excellent coffee within these standards has been a considerable problem, as evidenced by consumers' exclamations of surprise and pleasure on the occasions when a coffee brew is truly successful. This problem is compounded when brewing a small amount of coffee, i.e. 2-3 cups, in any of the currently popular coffee-making devices having relatively large capacities, i.e. 10-20 cups. The proper brewing process according to CBC, requires six ounces of heated water to flow through each ten grams of coffee grounds, with a time period of approximately seven minutes elapsing for the water to traverse the bed of grounds. When one wishes to brew a small quantity, i.e. 10-15 grams of ground coffee in a large apparatus, there is the problem that this small quantity produces a shallow bed of grounds through which water flows quickly with insufficient brewing time; other shapes of brew baskets and beds of coffee therein produce other problems; for example a conical shape with a narrow bottom-end results in non-uniform distribution of water through the bed; another problem is the tendency of the water and grounds to foam, causing back-up of the water and flooding. To selectively vary the strength of the brew within the acceptable range of hydrometer readings and allowable brewing time, has been even more elusive a task with presently available apparatus.
It is an object of the present invention to provide a coffee maker capable of consistently brewing excellent-tasting coffee, while varying the quantity of the brew and varying the strength of the brew from weak to strong. Accordingly, this invention provides a complete coffee maker, and also a new brewing basket operable with known coffee making apparatus that produces hot water to be dripped through the basket.